Crystal Population Growth in a Continuous Helically Coiled Flow Tube Crystallizer

A helically coiled flow tube crystallizer was investigated as a novel device for the shape‐selective generation of crystals with potassium alum as the model solid. The shape evolution of the crystal population was analyzed for growth‐dominated seeded cooling crystallization. The macro‐mixing behavior was characterized by residence time distribution measurements for the fluid phase and the crystals. At the crystallizer outlet, a flow‐through microscope was used to analyze the crystal size and shape distribution, where the 3D shape of individual crystals was estimated from 2D projections. The experiments showed a separation of the particle population according to the crystal size. This process allows the controlled shaping of crystals under continuous operating conditions.